• journal_title：Geophysics
• Contributor：Jianfeng Zhang ; Jincheng Xu ; Hao Zhang
• Publisher：Society of Exploration Geophysicists
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.1190/geo2011-0447.1
• journal_abbrev：Geophysics
• issn：0016-8033
• volume：77
• issue：5
• firstpage：S117
• section：Seismic Migration

We have developed a modified 3D prestack time migration (PSTM) scheme that can handle rugged topography as well as high near-surface velocities in land seismic imaging. The proposed topography PSTM can be applied to seismic data recorded on a 3D irregular surface without static corrections. Two effective velocity parameters were found to describe wave propagation through inhomogeneous media above and below a chosen datum. As a result, wave propagation phenomena in the complex near surface, such as near-vertical incidences through a weathering layer and raypaths bending away from vertical in the presence of high near-surface velocities, are correctly considered. The two effective velocity parameters can be estimated by flattening events in imaging gathers. Hence, it is not necessary to have detailed knowledge of the near-surface velocity model and velocity field below the datum when applying topography PSTM. We integrated residual static corrections into topography PSTM. This eliminated the distortions along the events better than conventional residual static corrections, which are usually applied before migration. The computational cost of the topography PSTM was only slightly higher than that of conventional PSTM due to the use of a table-driven algorithm. Three-dimensional synthetic and field data sets were used to test the proposed topography PSTM. High-quality imaging results were obtained.